Surface-mounted oscillators are compact and lightweight. Therefore, the surface-mounted oscillators are built into portable type electronics such as mobile phones, for example, as frequency and time reference sources. As one of such surface-mounted oscillators, there has been proposed a surface-mounted oscillator (an H structure type), in which a case main body includes concave portions on both principal surfaces thereof, and a crystal element is housed in one concave portion and an IC chip is housed in the other concave portion, for example.
FIGS. 4a and 4b are diagrams for explanation of a related-art surface-mounted oscillator, in which FIG. 4a is a cross-sectional view thereof, FIG. 4b is an outer bottom view thereof, and FIG. 4c is a plan view of a crystal element of the related-art surface-mounted oscillator (see, for example, PTL 1).
The surface-mounted oscillator includes a case main body 1, which is formed into an H shape in cross section having concave portions on both principal surfaces thereof, and which is formed into a rectangular shape in a plan view. The surface-mounted oscillator is configured such that a crystal element 2 and an IC chip 3 are housed in the case main body 1, and at least the crystal element 2 is hermetically encapsulated with a metal cover 4. The case main body 1 is made of laminar ceramics, for example, and includes a central bottom wall and upper and lower frame walls forming the concave portions on both principal surfaces thereof. A metal ring 5 is provided on the top surface (opening end face) of the upper frame wall that is one concave portion of the case main body 1. A crystal holding terminal 6 is provided on the inner bottom face of the one concave portion of the case main body 1.
Mounting terminals 7, which are formed into hook shapes striding over the adjacent sides at right angles, for example, are provided on the four corner portions of the lower surface (outer bottom face) of the lower frame wall which is the other concave portion of the case main body 1. Circuit terminals 8 are provided on an inner bottom face of the other concave portion of the case main body 1. With respect to the mounting terminals 7, the positions on the four corner portions are usually standardized, and for example, a power source terminal 7(Vcc), an output terminal 7(OUT), a ground terminal 7(GND), and a voltage control terminal 7 (Vc) are arranged on the four corner portions in this order counterclockwise beginning at the diagonally lower left position, for example.
The respective mounting terminals 7 (Vcc), 7 (OUT), 7 (GND), 7 (Vc) are electrically connected to respective circuit terminals 8 on the inner bottom face of the other concave portion of the case main body 1 through wiring paths (not shown). Then, a protrusion 9 is provided so as to be along the direction of long sides of the case main body 1, for example, to the voltage control terminal 7(Vc) differently from the other mounting terminals 7(Vcc), 7(OUT), 7(GND), and the positions and directionality (length direction) of the respective mounting terminals 7 (Vcc), 7(OUT), 7(GND), 7(Vc) are specified by use of the protrusion 9 as an identifying mark.
The crystal element 2 includes excitation electrodes 10a on both principal surfaces thereof, and leading electrodes 10b are respectively extended out so as to be folded to the opposite surface on both sides of one ends. Both sides of the crystal element 2 where the leading electrodes 10b are extended are firmly fixed to the crystal holding terminal 6, which is provided on the inner bottom face of the one concave portion of the case main body 1, with an electrically conductive adhesive 11. The crystal holding terminal 6 is connected to the circuit terminals 8 (crystal terminals) in the other concave portion of the case main body 1 through wiring paths (not shown). Then, the metal cover 4 is bonded to the metal ring 5 provided on the opening end face of the one concave portion of the case main body 1 by seam welding, to hermetically encapsulate the crystal element 2.
The IC chip 3, in which at least oscillator circuits (not shown) are integrated, includes an IC terminal (not shown) on its principal surface serving as a circuit forming surface. Then, the IC chip 3 is firmly fixed to the circuit terminals 8 in the other concave portion of the case main body 1 with ultrasound thermal compression bonding by use of bumps 12, for example, to be electrically and mechanically connected to the circuit terminals 8. Usually, resin 13 (so-called underfill) for specifically protecting the circuit forming surface is injected to the other concave portion of the case main body 1 and is applied so as to cover the IC chip 3.
In such an surface-mounted oscillator, for example, in the process for manufacturing including an inspection process for an oscillation characteristic of the surface-mounted oscillator, the protrusion 9 of the voltage control terminal 7 (Vc) as an identifying mark is recognized by image processing. Then, it is judged whether the directionality in a length direction of the surface-mounted oscillator is correct or not, and the surface-mounted oscillator is conveyed to the following process. In this case, since the surface-mounted oscillator (case main body 1) has a rectangular shape in a plan view, the position of the voltage control terminal 7 (Vc) having the protrusion 9 serving as an identifying mark is on the diagonally upper left side or diagonally lower right side. Then, in the case where the voltage control terminal 7 (Vc) serving as an identifying mark is on the diagonally upper left side, it is judged as “correct,” and the surface-mounted oscillator remains as is conveyed to the following process. Further, in the case where the voltage control terminal 7 (Vc) having the protrusion 9 serving as an identifying mark is on the diagonally lower right side, it is judged as “incorrect,” and the surface-mounted oscillator (case main body 1) is inverted to be conveyed to the following process.
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(PTL 1)JP-A-2009-27469